Wakatobi Archipelago coral reefs

Category: Marine and Oceanic Biomes.

Geographic Location: Asia.

Summary: This biome hosts a large degree of reef biodiversity with local and global ecological and economic importance, and is supported by a huge effort for its conservation.

The Wakatobi Archipelago coral reefs are located off the southeast tip of Sulawesi, Indonesia, the world’s eleventh-largest island. The archipelago’s name is actually an acronym given for the four main Tukanbesi islands: Wangi-wangi, Kaledupa, Tomia, and Binongko. These small islands, located between the Banda and Flores Seas, house huge coral-reef biodiversity. Hundreds of species of corals, fish, and marine invertebrates call these reefs home and make it one of the most biologically impressive locations on Earth.

The region has been designated as a marine national park—the Wakatobi National Park—and local and international efforts have been influential in conserving this biome. Since 2005, the park has been listed as a tentative United Nations Educational, Scientific, and Cultural Organization (UNESCO) World Heritage Site.

The Wakatobi Archipelago has 25 groups of coral reefs, including fringing reefs, barrier reefs, and atolls, totaling about 375 miles (600 kilometers) in circumference. Numerous other small islands also exist in the archipelago. These islands are all composed of coral that was deposited in previous environments over millions of years. The underwater explorer and conservationist Jacques Cousteau called this area ‘underwater nirvana,’ and Wakatobi is now one of the most popular diving locations in the world.

Biodiversity

The species richness of the Wakatobi coral reefs is staggering. There are about 850 known coral species globally, and these reefs possess about 750 of these species. A survey conducted in the Wakatobi National Park in 2003 identified 396 species of coral belonging to 68 genera and 15 families. These include Acropora formosa, A. hyacinthus, Psammocora profundasafla, Pavona cactus, Leptoseris yabei, Fungia molucensis, Lobophyllia robusta, Merulina ampliata, Platygyra versifora, Euphyllia glabrescens, Tubastraea frondes, Stylophora pistillata, Sarcophyton throchelliophorum, and Sinularia spp.

More than 900 fish species can be found on these reefs, and hundreds of additional species of marine invertebrates are evident. Fish species include the peacock grouper (Cephalopholus argus), bluespine unicornfish (Naso unicornis), titan triggerfish (Balistoides viridescens), two-spot snapper (Lutjanus biguttatus), spotted rabbitfish (Siganus guttatus), ovalspot butterflyfish (Chaetodon specullum), beaked coralfish (Chelmon rostratus), and longfin bannerfish (Heniochus acuminatus), to name just a few.

The reefs support many seabirds, including the brown booby (Sula leucogaster plotus), Malaysian plover (Charadrius peronii), and common kingfisher (Alcedo atthis). Marine turtle species, including the hawksbill seaturtle (Eretmochelys imbricata), loggerhead seaturtle (Caretta caretta), and Pacific ridley seaturtle (Lepidochelys olivacea), also inhabit the reef’s surroundings.

Humans derive many resources from the Wakatobi reefs. Many fish and marine invertebrates are captured for food (for private as well as commercial consumption), while others are exported as ornamental species that are found in fish tanks worldwide. There are about 93 species of ornamental and commercially valuable fish. Unfortunately, overfishing, population growth, tourism, and global climate change are threatening these reefs to some degree.

Human Impact

Some fishing practices have had detrimental effects on reef health. First, certain species, especially large, pelagic fish, are exploited preferentially over smaller, benthic (deepwater) fish. This causes trophic cascades that disrupt the overall biome food web. Additionally, overfishing has become a major problem as human populations continue to grow on the various islands throughout Wakatobi. This can be exacerbated by the method of fishing, with blast fishing and cyanide fishing having harmful effects on the environment.

Corals, the basis of the biome, are also negatively affected in many ways. Water quality can have a profound impact, as human-induced terrestrial runoff causes turbid water, which blocks the sunlight needed by the symbiotic zooxanthellae that exist within the coral polyps. These single-celled organisms are essential for providing nutrients to reef-building coral.

Likewise, the loss of grazing fish can cause algae levels to grow, also stealing valuable sunlight. Finally, changes in water chemistry due to climate change could be detrimental to many coral species. Coral bleaching is a consequence of these scenarios and has been observed on Wakatobi reefs. Fortunately, no widespread bleaching events have been observed here yet.

Because of the high ecological and economic importance of the coral reefs, more than 5,000 square miles (13,000 square kilometers) of islands, reefs, and surrounding waters were established as Wakatobi National Park (WNP) in 1996. This immense park is one of a growing number of marine parks worldwide, and is the third-largest in Indonesia.

As part of a rapid ecological assessment, a management plan was put into place to help protect the important coral reefs. The objectives of this plan are to improve management in the park in ways that can be supported by most stakeholders, to initiate monitoring to assess where further management is needed and how effective management has been, and to garner support by increasing stakeholders’ understanding and appreciation of the WNP and its management.

International groups have also been influential in Wakatobi coral reef conservation. The Nature Conservancy and the World Wildlife Fund of Indonesia helped Wakatobi adopt a zoning system approved by all forms of government and by the communities living within the WNP. These groups also worked directly with the WNP’s local communities to make them more aware of their effects on the fisheries and the environment. Establishing no-take areas helped populations rebound, benefiting the local communities and the overall biome. Efforts have also been made to provide training in marine protected area management and to encourage sustainable tourism in the region.

Although global climate change is impacting the archipelago, conservation measures have mostly protected the coral reefs from a phenomenon known as bleaching. Coral bleaching events may have occurred because of elevated sea surface temperatures in the area. Bleaching is caused when higher than normal sea temperatures make light toxic to the coral’s food-producing symbiotic algae, the zooxanthellae. Under these conditions the zooxanthellae are expelled from the coral polyps, which then turn white. Bleaching causes corals to starve and is a temporary state; if thermal stress reverses, corals can return to their normal condition—but if the stress persists, corals can die in great numbers.

One of the management strategies to address this issue is to identify reef sites which may be more resilient to changing water temperatures, and include them in marine protected areas. It is thought that reducing direct human threats in these critical areas, such as destructive fishing and overfishing, will increase the chance that coral reefs will survive from climate change impacts.

The combined efforts of the Indonesian government, local stakeholders, and international conservation organizations provide hope that the Wakatobi coral reefs will persist into the future.

Bibliography

Clifton, Julian, Richard K. F. Unsworth, and David J. Smith., eds. Marine Research and Conservation in the Coral Triangle: The Wakatobi National Park. Hauppauge, NY: Science Publishers, 2010.

Haapkyla, J., R. K. F. Unsworth, A. S. Seymour, J. Melbourne-Thomas, M. Flavell, B. L. Willis, and D. J. Smith. “The Spatio-Temporal Coral Disease Dynamics in the Wakatobi Marine National Park, South-East Sulawesi, Indonesia.” Diseases of Aquatic Organisms 87, nos. 1–2 (2009).

“Keeping Things Colorful.” Wakatobi Flow, 10 Sept. 2019, blog.wakatobi.com/keeping-things-colorful/. Accessed 18 Aug. 2022.

Wilson, J. R., R. L. Ardiwijaya, and R. Prasetia. “A Study of the Impact of the 2010 Coral Bleaching Event on Coral Communities in Wakatobi National Park.” The Nature Conservancy, Indo-Pacific Division, Indonesia, 7 (2012).